Carboxylation process

ABSTRACT

A method of carboxylating indene, cyclopentadiene, fluorene and hydrocarbyl cyanide by contacting said compounds with carbon dioxide under substantially anhydrous conditions in the presence of a guanidine of the formula: WHERE R1 through R5 are hydrogen or alkyl of from one to five carbons and acidifying the resultant reaction mixture to form the carboxylic acid derivative and recovering said derivative therefrom.

United States Patent Pa tmore [54] CARBOXY LATION PROCESS [72] Inventor: Edwin L. Patmore, Fishkill, N.Y. [73] Assignee: Texaco Inc., New York, N.Y.

[22] Filed: Feb. 3, 1971 [21] Appl. No.: 119,427

Related US. Application Data 7 [62] Division of Ser. No. 784,945, Dec. 18, 1968.

[52] US. Cl. .......260/5l5 R [5 1] Int. Cl ..C07c 63/44 [58] Field of Search ..260/515 R [56] References Cited UNITED STATES PATENTS 2,778,848 l/l957 Neuman et al ..260/533 A 2,954,410 9/l960 Frank et al ..260/515 R 3,275,686 9/1966 Kurtz ..260/515 R 3,595,907 7/1971 Patmore et al ..260/533 A l 5l- 3,694,496 [451 Sept. 26, 1972 Primary Examiner-James A. Patten Attorney-K. E. Kavanagh et al.

[5 7] ABSTRACT A method of carboxylating indene, cyclopentadiene, fluorene and hydrocarbyl cyanide by contacting said compounds with carbon dioxide under substantially anhydrous conditions in the presence of a guanidine of the formula:

where R through R are hydrogen or alkyl of from one to five carbons and acidifying the resultant reaction mixture to form the carboxylic acid derivative and recovering said derivative therefrom.

3 Claims, No Drawings BACKGROUND or INVENTION This invention is in the field of art relating to the preparation of a carboxylic acid compound derived from hydrocarbons and aralkyl cyanides.

In the past, the carboxylic acid derivatives of the reactants contemplated herein were prepared by employing I very expensive bases such as sodium, naphthalene, sodamide, and lithium salts such as butyl lithium. The bases of the prior art being'costly,

rendered the process of preparing carboxylic acids of I the typecontemplated herein not practicable from a commercial point of view even though the carboxylic products were very useful as chemical intermediates for the preparation of barbiturates synthetic lube oil additives and other chemical compounds.

SUMMARY OF INVENTION where R through R are hydrogen or alkyl of one to five carbons, subsequently acidifying the resultant reaction mixture and recovering the carboxylic acid derivative therefrom.

DETAILED DESCRIPTION OF THE INVENTION Specifically, the method comprises forming a carboxylic acid compound of the group of indene-B-carboxylic [5.21.0 deca-3,8- diene-4,9-dicarboxylic acid and tricyclo [5.2.1.0 ']deca-3,8-diene-4,9-dicarboxylic acid or fluorene-9- carboxylic acid comprising contacting an organic reactant of R ..CH- ,CN, indene, cyclopentadiene, or fluorene, respectively, where R is aralkyl of from six to l I carbons in the presence of a guanidine of the formula:

where R through R are as heretofore defined under substantially anhydrous conditions with carbon dioxide desirably in excess of the stoichiometric amount at a temperature between about 0 and 250C., preferably between 25 and C, under a carbon dioxide pressure of from 1 to 500 atmospheres, preferably between 50 and 200 atmospheres, utilizing a mole ratio of base to organic reactant of between about 1:1 and 20:1, preferably between 1:1 and 5:1. As a next step the reaction mixture is acidified to a pH of less than 6, preferably between about I and 3, and the resultant carboxylic product acid is recovered therefrom.

Acidification is desirably conducted at a temperature of between about 5 and 35C.

A liquid solvent for the reaction would normally only be required to provide liquid reaction mixture conditions for atmosphereic pressure contactings. Suitable inert solvents are dimethyl sulfoxide, diphenyl sulfoxide, dimethyl sulfone and dimethylformamide.

In addition to the indene, cyclopentadiene and fluorene reactants contemplated herein are benzyl cyanide, p-methylphenylacetonitrile, p-ethylphenylacetonitrile and p-propylphenylacetonitrile.

Specific examples of the carboxylic products contemplated herein in addition to those previously mentioned are a(p-methylphenyl)cyanoacetic acid,a-(pethylphenyl)cyanoacetic acid and a-(p-isopropylphenyl))cyanoacet ic acid.

Specific examples of the acidifying acid contemplated herein are aqueous mineral acids of between about 4 and 96 wt. concentration such as hydrochloric'acid, nitric acid, sulfuric acid, and hydrobromic acid.

The carboxylic acid product is recovered by standard means such as by extraction, distillation and combinations thereof.

By the term substantially anhydrous water contents less than 0.5 wt. are intended based on the reaction mixture.

The following examples further illustrate the invention but are not to be construed as limitations thereof.

EXAMPLE I This example illustrates the preparation of indene-3- carboxylic acid from indene.

.To a glass lined 0.5 liter rocker bomb there was charged 11.6 grams of indene and 11.5 grams of l,1,3,3-tetramethylguanidine. The resultant mixture had a water content less than 0.5 wt. The bomb was assembled and flushed with dry carbon dioxide and additional dry carbon dioxide was charged to an initial pressure of 800 psig. The bomb was then rocked and heated at 98-l02C. for a 5 hour period and during that time the pressure increased to between 1,000 and 1025 psig. The bomb was allowed to cool and was vented. The reaction mixture was worked up by acidifying with cold aqueous hydrochloric acid (200 mls. conc. BC] 100 grams of ice and 100 mls. of 6 molar HCl) and the resultant acidic mixture was extracted with ether (1x200 MLS and 5Xl00 mls). The ether extracts were combined and the combined extracts were further extracted with a 10 wt. aqueous sodium bicarbonate solution (5x100 mls.). The bicarbonate extractions were cooled in ice water bath and made acidic with 6 molar HCl which was added until a pH of 3 was obtained. The yellow solids were formed which were further extracted with ether (6x100 mls.). The ether solution was dried over anhydrous sodium sulfate followed by drying over anhydrous calcium sulfate. The ether was stripped off on a rotating evaporator to give a crude acidic product and the crude acidic product was recrystallized from benzene to yield 6.9 grams of indene-3-carboxylic acid, corresponding to a yield of 43.3 mole percent yield basis indene reactant. The melting point of the indene carboxylic acid was l59l6lC. (lit. l58-l60C.). A mixture melting point of the product and a sample of known pure indene-B-carboxylic acid was not depressed. The infrared and nuclear magnetic resonance spectra confirmed the presence and structure of the indene-3-carboxylic acid product.

EXAMPLE II To a glass-lined, 0.5 liter pressure bomb, 14 grams of benzyl cyanide and 13.8 grams of l,l,3,3-tetramethylguanidine were charged and the bomb was assembled and flushed with dry carbon dioxide. The resultant mixture had a water content less than 0.5 wt. Then additional dry carbon dioxide was charged to an initial pressure of 900 psig. The bomb was rocked and heated at 2833C. and at 900-950 psig carbon dioxide pressure for 8 hours. The resultant reaction mixture was acidified and the carboxylic product recovered in the manner described in Example I. The product weighed 0.5 grams and was identified as alpha-phenylcyanoacetic acid. The melting point of the alpha-phenylcyanoacetic acid was 9194C. (lit. 92C.) and the infrared and nuclear magnetic spectra confirmed the structure.

EXAMPLE lll To a 3-necked 100 ml., round-bottomed flask equipped with a magnetic stirrer, thermometer, gas sparger, heating mantle and condenser, the exit of the condenser being connected to a mercury bubbler, there was charged 13.2 grams of cyclopentadiene and 23 grams of 1,1,3,3-tetramethylguanidine under atmospheric pressure conditions. The resultant mixture had a water content less than 0.5 wt. D ry carbon dioxide was bubbled under atmospheric pressure into the mixture of a period of 3 hours at 29-40C. The resultant product was acidified and worked up in accordance with Example I and 2.7 grams of tricyclo [5.2. l .0 'b]deca-3,8-diene-4,9-dicarboxylic (Thieles acid) representing a yield of 12.3 mole percent was obtained. The melting point of the product was l204C. (lit. 204205C.) and an infrared spectral analysis confirmed the production of Thieles acid. 1

EXAMPLE IV To a glass line, 0.5 liter bomb there was charged 26.4 grams of cyclopentadiene and 46 grams of l,l,3,3- tetramethyl guanidine. The bomb was assembled and flushed with dry carbon dioxide. The water content in the resultant mixture was less than 0.5 wt. Then additional carbon dioxide was charged to an initial pressure of 850 psig. The mixture was rocked and heated to 73-77C. and at 900-925 psig. carbon dioxide presacid sured for five hours. The bomb was allowed to cool and vented through a trap cooled with dry ice isopropyl alcohol. The resultant reaction mixture was acidified with cold aqueous HC] (200 mls. of con. HCl+200 mls. of water g. of ice) and the acidified mixture was extracted with ether (1x200 mls.). At this point solids formed in the ether extract and the ether extracts were filtered through a sinter glass filter, the solid residue on the filter washed several times with water, air dried, and dried in a vacuum at room temperature to give tricyclo [5.2.1.0 deca-3,8-diene-4,9-dicarboxylic acid (9.2 grams) representing a yield of 20.9 wt. The product had a melting point of 202208C. and an infrared spectrum confirmed structure.

The separated aqueous layer from acidification was worked up by ether extraction (6Xl50 mls.) followed by extraction of the ether with 10 percent aqueous sodium bicarbonate (5Xl00 mls.) and acidification of the sodium carbonate extracts with dilute hydrochloric acid to a pH of about 3 to give a second solid in the form of a precipitate having a weight of 7 grams. The second solid precipitate was tentatively identified as tricyclo-[ 5 .2. 1.0] deca-3,8-diene-5 ,Sdicarboxylic acid representing a yield of 15.9 wt. of the cyclopentadiene reactant. The infra-red spectral analysis of the second precipitate confirmed the structure.

EXAMPLE V This example illustrates the criticality of the particular combinations of reactants defined herein. Four runs were conducted in which the reactant or base material was substituted with substances closely related to the reactant or base contemplated herein. In Runs A and C the overall procedure was that as essentially described in Example III. In Run B the overall procedure was that essentially described in Example IV. The water content in the initial reaction mixture was less than 0.5 wt.

TABLE I React. Cond.

and Results A B C Base 'TMG "IRA-400 NaOH Moles Base 0. l2 0.06 0.24 Reactant Phenylacetylene lndene lndene Moles of Reactant 0.03 0.06 0. l 2 CO, Temp., C. l00-l02 46-51 31-60 CO, React. Time, hrs. 4 8 2 CO: pressure, psig 975-1000 COOH Derivative, None None None yield l ,l ,3,3-tetramethylguanidine Polystyrene quaternary amine less than 6 and recovering said carboxylic acid therefrom, said R through R being hydrogen or alkyl of from one to five carbons.

2. A method in accordance with claim 1 wherein said acidifying is conducted to a pH of between about I and 3.

3. A method in accordance with claim 2 win said acidifying acid is aqueous hydrochloric acid.

i II I I! 

2. A method in accordance with claim 1 wherein said acidifying is conducted to a pH of between about 1 and
 3. 3. A method in accordance with claim 2 win said acidifying acid is aqueous hydrochloric acid. 